A highly active beta-glucanase from a new strain of rumen fungus Orpinomyces sp.Y102 exhibits cellobiohydrolase and cellotriohydrolase activities

作者：Chen Yo Chia; Chen Wan Ting; Liu Jeng Chen; Tsai Li Chu; Cheng Hsueh Ling^*

来源：Bioresource Technology, 2014, 170: 513-521.

DOI：10.1016/j.biortech.2014.08.016

• Exocellulase
• Rumen fungus
• Cellobiohydrolase
• Cellotriohydrolase
• Orpinomyces

A new strain of rumen fungus was isolated from Bos taurus, identified and designated Orpinomyces sp.Y102. A clone, celC7, isolated from the cDNA library of Orpinomyces sp.Y102, was predicted to encode a protein containing a signal peptide (Residues 1-17), an N-terminal dockerin-containing domain, and a C-terminal cellobiohydrolase catalytic domain of glycoside hydrolase family 6. CelC7 was insoluble when expressed in Escherichia coli. Deletion of 17 or 105 residues from the N-terminus significantly improved its solubility. The resulting enzymes, CelC7(-17) and CelC7(-105), were highly active to beta-glucan substrates and were stable between pH 5.0 and 11.0. CelC7(-105) worked as an exocellulase releasing cellobiose and cellotriose from acid-swollen Avicel and cellooligosaccharides, and displayed a V-max of 6321.64 mu mole/min/mg and a K-m of 2.18 mg/ml to barley beta-glucan. Further, the crude extract of CelC7(-105) facilitated ethanol fermentation from cellulose. Thus, CelC7(-105) is a good candidate for industrial applications such as biofuel production.

• 出版日期2014-10